> From: Jaco De Villiers [mailto:jac...@infoslips.com] > > When I encrypt data (zero padded) using Rinjael in my C# application and > then encrypt the same data using the BouncyCastle portable library then I > get a similar result expect that the BouncyCastle library adds 16 bytes at the > end of the encrypted data. Rinjael returns 160 bytes and BouncyCastle > returns 176 bytes of which the first 160 is the same as the Rinjael library
Rijndael is just a block cipher. It will always encrypt blocks of 16 bytes, so if your output is a different size, it means your input was a different size. I suggest you double-check what your exact input is - After padding, evidently, you're getting an extra block. Normally you don't want to use zero-padding, because it's impossible to distinguish a series of zeroes from a series of real data that happen to end in zeroes. Zero padding is only for when you know the exact length of your data, but it's not a multiple of the blocksize. If you know the exact length of your data is a multiple of blocksize, then use No padding. For normal usage, I would suggest basically any other padding scheme - PKCS7, X923, or ISO10126, are the ones supported by the Microsoft AES classes.
